Microsoft made a new pitch Wednesday to app makers, promising an audience of more than a billion people if they develop services for the upcoming Windows 10 operating system.

Microsoft made a new pitch Wednesday to app makers, promising an audience of more than a billion people if they develop services for the upcoming Windows 10 operating system.

The US technology titan opened its annual Build developers conference with a three-hour keynote presentation highlighting how Windows 10 will let software savants serve up creations on the full spectrum of smart devices, including HoloLens augmented reality headgear.

And, to make it even simpler, they will be able to re-use code written for apps they have made for Apple or Android devices.

Microsoft also revealed that the successor to its Internet Explorer browser has been named "Edge."

"For us the name refers to being on the edge of consuming and creating," operating systems group corporate vice president Joe Belfiore said during the presentation."It's a browser that end users will think about for getting things done."

From Apple to Windows

The bulk of the presentation was aimed at winning over developers whose fun, functional or hip applications can make smartphones, tablets or other devices hits with consumers.

"Microsoft is making a major play to win back developers," said Forrester analyst Michael Facemire.

"They've opened up the once-impenetrable castle walls, allowing development using a wide range of languages, platforms, and tools."

Windows phones and tablets have lagged behind those powered by Apple or Google Android software and part of the reason is a lack of must-have applications for anything from games to exercise routines.

Windows 10 is designed to power all kinds of devices from wearable computers to smartphones or desktop machines, and an application needs to be written just once to perform on all of them, according to Microsoft chief executive Satya Nadella.

"Windows 10 represents a new generation of Windows built for an era of more personal computing," Nadella said.

Nadella added that "the mobility of the experience is what matters, not the mobility of the device."

Microsoft announced availability of tools that will let developers power Windows 10 applications by re-using code they have already written to make applications for Android or Apple mobile devices.

The move promised to save developers time and money making versions of apps for Windows phones or tablets.

"With Apple, you choose to invest in Mac OS or iOS; with Google you invest in Android or Chrome OS," said Microsoft executive vice president of operating systems Terry Myerson.

"Windows is the only ecosystem that let you bring your apps to all these devices, officially."

To get Windows 10 adopted quickly, Microsoft plans to give it away as a free upgrade for a year after its release.

"Our goal is that in two to three years of the release, a billion devices will run on Windows 10," said Myerson.

Microsoft has also been bulking up its Azure data handling services run in the cloud to let developers tap into machine learning analytics as well as massive computing power as needed, according to Nadella.

"This conference is all about celebrating and challenging the creativity and the ingenuity that you all bring to build new and great things on top of platform innovations that we make available to you," he told the gathering of developers.

Flex and fit apps

Microsoft has a vision that Windows and apps written for the platform should "flex and fit" different size screens without needing any new software code to be written, according to Belfiore.

Microsoft brought hundreds of its yet-to-be-released HoloLens visors to Build to let developers experience applications designed for no screens at all, but with imagery overlaid on the real world.

"People, not devices, are mobile," said Microsoft's Alex Kipman, who played a part in creating HoloLens.